the flyin' scotsman

My car has developed a transmission oil leak that is progressively getting worse (not that I really thought it would fix itself). Started with a few drops falling on the garage floor just ahead of the rear wheels. Took the RR wheel off a week ago cleaned up the area with no apparent location of the seepage. Yesterday the few drops have become substantially more to the point I can smell the oil possibly burning on the exhaust (yikes!).

Is there a more likely location for this leak to occur? Really hopeful for an easy fix............want to drive the max for the remainder of our very short season

dr bob

"...in front of the rear wheels" is a big patch of real estate. That said, the culprits tend to be a loose filler cap, a leaking o-ring at the reservoir-to-pan-tube seal, leaking pan gasket, leaking torque converter seal. Clean everything up under there, run it and see where it's coming from. The torque converter seal dribbles out the little grate slots under the front of the trans, so when driving the oil gets windblown over the stuff behind it. When sitting it drops straight down, and a little may migrate back to the main body and look like a pan leak at the front edge.

Fixing the first few is fairly simple. The torque converter seal requires that you pull the trans down, and there's a list of WYAIT things you'll want to consider. Torque converter bearings for sure, and possibly the torque tube if you have any noise from it. The TT slides right out with the trans out of the way.

There are also some AT cooler hoses running along the frame rail that can leak if they are damaged. There are rubber sections that have been known to leak, so look at them too.


Still a week of summer left in Ab, right?

the flyin' scotsman

Thanks Bob ............I'll do more work this morning; clean the area, go for a quick spin, back in the garage for a recheck. Hope the issue is one of the first 3 on your list.


We are hopeful that with Mars being so close that we get another 6 weeks before the Artic winds bring our longest season

the flyin' scotsman

Jacked up the car this morning and the complete transmission including the torque convertor and mid exhaust silencers back have a misting of a/t fluid. Cleaned up as best I could, RR wheel back on and out for a quick spin. Transmission selects all gears whether at regular highway speeds or WOT as it always has..........back to the garage, RR wheel off, up in the air as high as I can get it with the floor jack and the a/t oil is dripping at a good rate from the holes/grating below the t/convertor.

So it loooks like the t.c. seal has gone ...........Bob has suggested that the transmission has to be dropped which appears most likely...........anyone with experience R&R the a/t, seal replacement, WYAI jobs.........thanks for all input.

Is it past noon yet............

BrianG

That sucks, Malcolm!

The good newsd is that you still have a bout 6 weeks until the "Road to the Sun" run. Spin them wrenches! We expect you along!

the flyin' scotsman

Sure does Brian...........'Run to the Sun' is still on the calendar.

I just read Tony's write up on dropping the tranny when he did his TT............sounds easy.........yeah right

Off to the garage to drop the exhaust system, undo the driveshaft etc. etc. etc.

See you all in a week or 2 ............I was going to install the Bilstien/Eibachs, modular X over exhaust etc before fall.........now I'm doing the work a little sooner.

algie928s4

WOW There!, good news maybe at the ready- if the oil is coming from the grating at the front of the grills (engine end) it's the convertor sump/drain plug - if it's at the rear of the grills it's the seal.
I had this a month ago and when you rotate the convertor so that you can see the sump it looks and feels dry, but the speed of rotation throws it onto the casing.
Check the manual troubleshooting section, it's spot on in describing problem, and as I was told by a helpful rennlister if the sump plug is either too tight or too loose it leaks and you really need the suggested thread sealant suggested.
You could search under my past posts for confirmation- go on be a PESSIMIST!

Garth S

In the words of the immortal bard, " that really sucks!". My first reaction was the convertor drain plug: I see the non-flying Scot (Algie) has already called that.
Have you done a trans fluid change this season? - ie - touched the drain plug? Very well worth a check - and keep the ATF reservoir topped up.
I have read of 'seal swelling' additives working - but I have no real first hand experience. I will take a visit to my buddy with a tranny shop - he is the best tech in the business around here, and may have a worthwhile recommendation for a "stop-gap" measure. On the bright side, the seal probably only costs a dollar
Also, google for the Mercedes forums - they publish a lot about their ( our) transmissions.

the flyin' scotsman

Algie............I'll check the convertor drain plug today.............good suggestion

Garth.........the fluid was not changed this Spring, only a quick level check but I'll check the xmission drain plug but the leak is from further forward (toward the engine). Hopefully your tranny friend has a good temporary suggestion which will extend my driving season 'till the snow flies

Garth S

Bardhal 'Stop Leak' could be added - but at a potential price that is too high for me! I took a look at a Mercedes box and had a chat with friend Rick ... who advised me ...
Seal swelling additives are not discriminating - and the Mercedes box is chock full of huge O-rings and many seals. To attempt to soften/swell the convertor seal will soften everything inside - which suggests that when rebuild comes along - absolutely everything should be replaced = majour overhaul. Knowing this, I'd sooner sweat it out without an additive, and plan on going in for the convertor seal(s) and bearings - and let the rest of the complicated box enjoy no more than fresh ATF fluid.
If it is truly the convertor seal that is leaking, it seems strange that it came on so suddenly. A progressive leak may be more in character. Anyway, check the (convertor) drain plug, and keep the level topped as you decide whether or not to continue driving until snowfall.
Steve Catanneo would have far more expertise to advise on this.

the flyin' scotsman

On one side of the scale is the 'quick' fix which as mentioned affects the entire xmission which may well indeed entail a complete rebuild when the leak starts again and can't be cured with more additive. On the other side is the time or $$$ required to drop the tranny and have the problem fixed properly.

After the check on the TC drain plug torque I'll be heading for the tranny drop. Fix the real problem and do it right.............now where's those air guns and sockets?

the flyin' scotsman

Update.............re-torqued the TC drain plug (thx to the SO for cranking the engine). Cleaned the area again w/ brake cleaner, removed 1.4l of fluid from the tranny, refilled with fresh ATF and Lucas additive...........NO LEAKS with the car at op. temp. *** end in the air.............big test tomorrow with the wheels on the ground.

There must be an easier way to fill the xmisson..............how?

dr bob

I bought a small gear-oil pump at the local parts place. Sta-Lube brand name on it but I've seen it in other flavors. The suction end threads nicely into a Mobil-1 Syn ATF bottle, other brands need a short section of hose to reach down to the bottom of the bottle. Outlet of the pump gets about three feet of vinyl tubing from Home Depot attached so I can see the fluid moving in the tube. A plastic tie wrap secures it to the right exhaust pipe, which is conveniently placed just above the filller cap. End in the reservoir, I can sit next to the rear wheel, watch the reservoir as I s-l-o-w-l-y pump ATF into the reservoir.

the flyin' scotsman

Bob..........sounds like an idea that'll work well.............I'll use it when I do the tranny/convertor flush this winter.

Tightening the convertor drain plug, adding 2 litres of fresh fluid and 700ml of Lucas trasmission additive seems to have the problem fixed. Hopefully I'm leak free for the remainder of the 'snow free season'.

Thanks all for comments and recommendations

the flyin' scotsman

Took the car for a 50km drive..........all is dry.

Has anyone transferred the level marks from the front of the reservoir to the rear? The rearward marks would be easilly visible with all 4 wheels on the ground!